1. Field of the Invention
The present invention relates to a disk cartridge for holding therein a disk used in a recording or reproducing apparatus for recording and reproducing business-application graphics files, computer data files, etc., or in a playback-only CD player or the like, and also relates to a disk clamping device for clamping such a disk. More particularly, the invention relates to a disk cartridge with a sliding cover, which, with a disk contained therein, is loaded into a recording or reproducing apparatus designed for use with such a cartridge, and also relates to a disk clamping device capable of clamping a disk regardless of whether the disk has a hub or not.
2. Description of the Related Art
Generally, conventional disks having a center hole therein, exemplified in particular by compact disks and laser disks, are inserted into recording or reproducing apparatus (hereinafter simply referred to as recording/reproducing apparatus) without using a protective case (such disks are hereinafter generally called the second disk). The second disk is therefore susceptible to damage due to dust, fingerprints, etc., which may make the recorded information unable to be read out. The second disk has the further disadvantage that it is not easy to handle when loading it into a recording/reproducing apparatus. Furthermore, since the second disk has a center hole only (hereinafter called the second center hole) that can be used for mounting, the recording/reproducing apparatus needs to be equipped with a disk clamping device for clamping the second disk in place. This not only makes the construction of the recording/reproducing apparatus complex, but increases the height of the construction.
In view of these problems, disks for newly developed and commercialized recording/reproducing apparatus (such disks are hereinafter generally called the first disk) are encased in disk cartridges (hereinafter called the first-disk cartridge) to prevent damage due to dust, fingerprints, etc. and to enhance the ease of handling. The first disk has a center hub made of magnetic metal; this serves to simplify the construction and reduce the height of the recording/reproducing apparatus. The center hole of the hub (thereinafter called the first center hole) is made to engage on the motor shaft that drives the turntable provided in the recording/reproducing apparatus, and the hub is attracted by a magnet fixed to the turntable, to clamp the first disk in place.
However, the second disk and the recording/reproducing apparatus designed for use with it have already established a large market, for example, in the form of CD players and laser disk players, and as data storage media for business-application graphics files, computer data files, etc. Therefore, in developing and commercializing new recording/reproducing apparatus having increased performance such as higher recording density, preserving compatibility with the second disk in reproduction or in both recording and reproduction becomes a major design consideration. To achieve this, the recording/reproducing apparatus needs to be designed so that the second disk, as well as the first disk encased in the first-disk cartridge, can be mounted and positioned in place.
The following three constructions, for example, are known in the prior art for enabling the second disk to be recorded or reproduced using the same apparatus designed for the first disk.
(1) In Japanese Laid-Open Patent Publication No. 4-362560 (the first prior art), a recording/reproducing apparatus is described that uses two different loading mechanisms, one for loading the second disk into a prescribed position and the other for loading the first-disk cartridge containing the first disk into a prescribed position.
(2) In Japanese Laid-Open Patent Publication No. 4-356766 (the second prior art), a second-disk cartridge is proposed that uses an adapter hub designed to be compatible with the hub of the first disk in loading and unloading; this adapter hub is manually attached to the second disk which is then loaded removably into the second-disk cartridge. According to the construction of the second prior art, either type of disk, the first disk with a hub or the second disk without a hub, can be mounted properly on the turntable in the recording/reproducing apparatus.
(3) In Japanese Utility Model Publication No. 3-25336 (the third prior art), there is proposed a second-disk holding device called a disk holder, not a disk cartridge, that is capable of removably holding the second disk, the construction being such that the second disk held in the holder is delivered onto the turntable when the holder case is loaded into a recording/reproducing apparatus. The holder case consists essentially of a first moving member, which is mounted directly onto a mounting part in a recording/reproducing apparatus, and a second moving member movable relative to the first moving member. In this disk holder, a tray on which the second disk is directly mounted, and which has an opening hole (hereinafter called the second opening hole) that permits the insertion therethrough of the turntable and head of the recording/reproducing apparatus, is installed, for example, in rotatable fashion, to the second moving member. When playing back the second disk, for example, the tray holding the second disk thereon is moved to the turntable of the recording/reproducing apparatus for reproduction, etc. This disk holder is so designed as to preserve mounting compatibility with a disk holder having, for example, six trays similar in construction to the above-described tray, and capable of holding a plurality of second disks, each tray being arranged, for example, in rotatable fashion in the case that is mounted on the mounting part in the recording/reproducing apparatus.
The above prior art constructions, however, have the following problems.
(1) In the first prior art, the recording/reproducing apparatus needs to be equipped with two loading mechanisms, one for loading the second disk and the other for loading the first disk. Furthermore, the first prior art requires that a disk clamping device for clamping the second disk from both sides thereof be provided in the recording/reproducing apparatus at a position opposite the turntable. This makes the construction of the recording/reproducing apparatus complex, and increases the size and cost of the apparatus.
In recent years, the demand for a built-in type recording/reproducing apparatus has been increasing rapidly for use in portable personal computers or the like, and with this trend, reducing the apparatus height has become an important design consideration. The first prior art, however, requires the provision of a disk clamping device, which tends to increase the height of the recording/reproducing apparatus, and hence has the problem of being unable to reduce the apparatus height.
(2) In the second prior art, no mention is made of how the mounting compatibility can be achieved between the second-disk cartridge capable of removably holding the second disk and the first-disk cartridge containing the first disk. For example, no description is given of how the positioning means, opening means for an externally exposed shutter, etc. can be designed compatible between the first-disk and second-disk cartridges.
Also, in the second prior art, the second-disk cartridge ejected from the recording/reproducing apparatus must be removed from the apparatus and be manually opened to remove the second disk contained therein. Furthermore, the second prior art requires that the adapter hub having mounting compatibility with the hub of the first disk be manually attached to the second disk. As a result, the user may have to spend much time trying to attach the hub properly, or may not be able to attach it because he has not acquired enough skill to do so. Thus the second prior art has the problem that the convenience of operation is greatly sacrificed.
(3) In the third prior art, the holder case is not provided with an opening hole that is exposed to the exterior thereof and that permits the insertion therethrough of the turntable and head of the recording/reproducing apparatus. The third prior art therefore has the problem that unlike a disk cartridge, the second disk as contained in the case cannot be directly placed in the recording or reproduction position for recording or reproduction.
In the disk holder of the third prior art, a spring or-like component, as a driving means for moving the second moving member relative to the first moving member, is installed between the first and second moving members, while the tray capable of directly holding the second disk thereon is attached rotatably to the second moving member. This essentially requires a relatively large number of component parts arranged in the height direction of the disk holder. Furthermore, the disk holder, though designed to accommodate one second disk, is constructed to have approximately the same size as the disk holder capable of containing a plurality of second disks, in order to achieve mounting compatibility between them. The third prior art therefore has the problem that the height of the disk holder cannot be reduced because of its construction.
Generally, to save the storing space when not in use, and to provide the convenience of portability, it is desirable that the disk cartridge height be reduced as much as possible while securing a sufficient space to allow the disk to rotate therein when the cartridge is mounted and positioned in the recording/reproducing apparatus. For example, for disks about 120 mm in diameter, the cartridge height usually is reduced to 10 mm or less. In the third prior art, however, in addition to the first and second moving members, such component parts as a spring and tray are placed one on top of another across the height of the disk holder, as described above. The third prior art therefore has the problem that it is extremely difficult to reduce the cartridge height to an optimum value, e.g. 10 mm or less for disks about 120 mm in diameter.
The third prior art has the further problem that unlike disk cartridges, the second disk as contained in the disk holder cannot be directly placed in the recording or reproduction position for recording or reproduction.
Furthermore, the following problem generally exists for the first-disk or second-disk clamping.
The recent trend in design is to reduce the diameter of the turntable to increase the recording area near the disk center and thereby provide larger recording capacity. This, however, reduces the size of the magnet built into the turntable and decreases the clamping force; the resulting problem is that the second disk, etc. cannot be clamped firmly on the turntable, causing disk slippage, and leading to trouble.